Theory of channel hot-carrier degradation in MOSFETs

A critical but still poorly understood process in metal-oxide-semiconductor held-effect transistors (MOSFETs) is stress-induced changes in device thre shold voltage, channel conductance, etc. which limit the operating lifetime s of the transistors. However, the degradation characteristics of deep-subm icron MOSFETs, the widely demonstrated deuterium/hydrogen isotope effect, a nd the related results of scanning-tunneling microscopy-based depassivation experiments on silicon-vacuum interfaces are providing new insights into t he degradation of MOSFETs via, at least, depassivation of the silicon-oxide interface. In this manuscript, we review the basic mechanisms of depassiva tion, suggest disorder-induced variations in the threshold energies for sil icon-hydrogen/deuterium bond breaking as a possible explanation for observe d sublinear time dependencies for degradation below t(0.5), and show that e xcitation of the vibrational modes of the bonds could play a significant ro le in the continuing degradation of deep-submicron MOSFETs operated at low voltages. (C) 1999 Elsevier Science B.V. All rights reserved.